Concrete construction



(No Model.)

E. L. RANSOME. CONCRETE CONSTRUCTION.

f To all whom it may concern:

UITED STATES PATENT irren,

ERNEST LESLIE RANSOME, OF OAKLAND, CALIFORNIA.

CONCRETE CONSTRUCT! ON.

SPECIFICATION forming part of Letters atent No. 516,113, dated March 6,1894. Application tiled November 6, 1893. Serial No. 490,185, (Nomodel.)

Fe it known that I, ERNEST Lustre RAN- SOME, a citizen of the UnitedStates, residing at Oakland, in the county of Alameda and State ofCalifornia, have invented an Imprcvement in Concrete Constructions; andI hereby declare the following to be a full, clear,

and exact description thereof.

4My invention relates to that class ot structnres of concrete,brickwork, or like material,

j in which the tensile strength of the construction is increased by theembedxnent and intreduction of iron bars into the body ot the i. 5osquare, onetenth twist to material, and is an improvement upon theconstruction for which Letters Patent No. 305,226, of September16,1S8l,were granted me. By that invention I created a continuons bondbetween the iron and concrete, by using polygonal bars of iron sotwisted as to form long spiral threads on the bars.

My present invention consists in using similar bars of iron in likemanner, that have been twisted cold, that is to say using bars ot ironwhich were twisted while the iron was in its normal condition,cold,instead ot being heated for the operation, for I have disoovered thatstructures in which cold-twisted hars are used are much more rigid andalso stronger and capable of sustaining greater loads than when suchbars are used hottwisted, or untwisted, and this quality ot coldtwistediron applies with equal force to iron of any cross section, whether itbe rounder square. The amount of twist to be given to the bar may varyconsiderably. The more they are twisted, the stronger and more rigid isthe structure in which they are used, provided the cold-twisting is notcarried too near to the point of rupture.

In practice I usually give as follows: bars one-fourth inch diameter, orsquare, six twists to the lineal foot; bars one-half inch diameter, orsquare, three twists to the lineal foot; bars three-fourths inchdiameter, or square, two twists to the lineal toot; bars one inchdialneter,*fory square, three-fourths twist to the linealitoot; bars oneand one-half inches diameter, or square, Onehalf twist to the lineal`^oot5`bars two inches diameter, or the lineal toot.

This twisting can be readily done in any ordinary iron lathe ofsuhicient strength, by rigidly fastening one end of the bar to theheadstock or face plate ot the lathe, and fastening the other end of thebar to the tailstock (both stocks being held also rigidly in theirrelative positions), and turning the lathe and bar inthe ordinary mannerot lathe turning.

The accompanying drawing illustrates the position of these bars in aslab of concrete.

ct, a, are supporting walls, h, a concrete slab, c, a cold twisted barembedded in the concrete for the purpose of increasing its tensilestrength.

For the purpose of this invention,I regard stone work, brick work,glass, or other structural substances of less elasticity than the barsof untwistcd iron, such as cast iron, as the equivalent of concrete. Andother metals that may be in like manner affected by coldtwisting as theequivalent of iron.

In many constructions this lessenin g of the ductility and elasticity ofthe iron would be of a greater disadvantage than the corresponding gainin strength due to the coldtwisting. But in concrete structures thelessening of the ductility of the iron of itself is a great and positivebenefit, and meetsua want long sought after, viz: that of causing theiron and the concrete in which it istan-- bedded to work harmoniouslyand in unison together when subjected to strain. The nearer theelasticity of the iron approaches that of the concrete withoutsacriiieing its strength, the better; because the more they areseparated from one another in degree the more certain is the concretestructure to crack and break when under strain.

Having thus fully described my invention, what I claim, and desire tosecure by Letters Patent, is

A structure of concrete or similar naterial having cold-twisted metalbars embedded in said material for strengthening the saine.

ERNEST LESLIE RANSOME.

Witnesses:

H. F. THOMSEN, MINNIE Pn'rnason.

